My friend bought a CarPlay/Android Auto unit from Carlink for his 2011 Q5 MMI 3G Plus. We installed it and it went quite well. It’s truly a plug and play unit. It does work with his new iPhone 11 Max. Although we didn’t test with an Android phone for Android Auto, but I’m sure it’s working also since the menu has them all. If you don’t have AMI, you must have an Auxiliary port so the MMI has the Auxiliary option for the CarPlay to have sound.
